For a natural synthesis, this isn't too bad. The shuttle forms the same way as the shuttles were built in the original breeder (i.e. 2 gliders for block, then glider+ship to make the shuttle).

Before creating a synthesis, however, it's often useful to determine whether a natural approach would be better than a synthetic one. In some cases, the natural approach wins (e.g. in the recent snark synthesis, 17 gliders were saved). In some cases, the synthetic approach wins.

In this case, your natural approach takes 10 gliders. A synthetic approach would be to synthesize the moose antlers (whichcan be doe from 4), and add the shuttle+block (which takes another 4), doing it for only 8.

Unless there would be a good alternative reason to do so (e.g. a less obtrusive synthesis (such as edge-shooting the shuttle), or a synthesis that completes more quickly, or a synthesis with all the gliders coming from 2 sides, or a slow salvo synthesis, or as an exercise in synthesis creation, etc.), it wouldn't be practical to create a natural synthesis that takes any more than 7 gliders - i.e. to tame the natural reaction, you could consider that you have a budget of 7 gliders to improve the state of the art, and if it takes more, it would be easier to stick with the natural one.